Poly(trimethylene terephthalate) (also referred to as “3GT” or “PTT”) has recently received much attention as a polymer for use in textiles, flooring, packaging and other end uses. Textile and flooring fibers have excellent physical and chemical properties.
Textured polyester yarns, prepared from partially oriented polyester yarns or spun drawn yarns, are used in many textile applications, such as knit and woven fabrics (e.g., as the yarn for the entire fabric, the warp, weft or fill, or as one of two or more yarns in a blend, for instance, with cotton, wool, rayon, acetate, other polyesters, spandex and/or combinations thereof, etc.) for apparel and upholstery (e.g., furniture and automotive). Poly(ethylene terephthalate) textured yarns are commonly used for this purpose. Howell et al., in U.S. Pat. No. 6,287,688 (which is incorporated herein by reference), have described preparing textured poly(trimethylene terephthalate) yarns and their benefits. The resultant yarns have increased stretch, luxurious bulk and improved hand, as compared to poly(ethylene terephthalate) yarns. Howell et al. describe preparing stable partially oriented poly(trimethylene terephthalate) yarns in a process with a spinning speed of up to 2600 m/m, and it has been desired to spin at higher rates.
Preparing stable partially oriented poly(trimethylene terephthalate) yarns at high speeds using poly(ethylene terephthalate) conditions has not worked well. After spinning, a partially oriented yarn is typically wound onto a tube, or package, and the yarn packages are then stored or sold for use as a feed yarn in later processing operations such as drawing or draw-texturing. A partially oriented yarn package is not useable in subsequent drawing or draw-texturing processes if the yarn or the package itself are damaged due to aging of the yarns or other damage caused during warehousing or transportation of the yarn package.
Stable partially oriented poly(ethylene terephthalate) yarns are typically spun at speeds of about 3,500 yards per minute (“ypm”) (3,200 meters per minute (“m/m”)). Since they typically do not age very rapidly, they remain suitable for downstream drawing or draw-texturing operations. In the past, attempts to make stable partially oriented poly(trimethylene terephthalate) yarns using a spinning speed in this same range have failed. The resulting partially oriented poly(trimethylene terephthalate) yarns have been found to contract up to about 25% as they crystallize with aging over time. In extreme case, the contraction is so great that the tube is physically damaged by the contraction forces of the yarn. In more common cases, the contraction renders the partially oriented poly(trimethylene terephthalate) yarns unfit for use in drawing or draw-texturing operations. In such cases, the package becomes so tightly wound that the yarn easily breaks as it is unwound from the package.
Spinning partially oriented poly(trimethylene terephthalate) yarns at slower speeds using equipment originally designed for partially oriented poly(ethylene terephthalate) yarns is inefficient. It is also problematic since the spinning and winding equipment is designed to run at higher speeds than those presently used for making poly(trimethylene terephthalate) yarns.
Spun drawn yarns are also used to make textured yarns, and there is also a desire to prepare spun drawn yarns at higher speeds.
It is also very desirable that the practitioner be able to make textured poly(trimethylene terephthalate) yarns from partially oriented and spun drawn poly(trimethylene terephthalate) yarns prepared at high speeds using the same or similar conditions to those produced at lower speeds. Thus, these yarns should have the same or similar elongations and tenacities.
Poly(trimethylene terephthalate) filaments and yarns have also been prepared for other purposes. For instance, bulked continuous filament (“BCF”) yarns, their manufacture, and their use in flooring, are described in U.S. Pat. Nos. 5,645,782, 5,662,980, and 6,242,091, which are hereby incorporated by reference. Fine denier yarns are described in U.S. Patent Publication Nos. 2001/30377 and 2001/53442, which are incorporated herein by reference, and direct use yarns are described in U.S. Patent Publication No. 2001/33929, which is incorporated herein by reference. Staple fibers can be made from multifilament yarns as described in WO 02/22925 and WO 02/22927, which are incorporated by reference. Spinning these yarns, as well as other poly(trimethylene terephthalate) yarns and filaments, at higher speeds can be advantageous. Therefore, the ability to spin poly(trimethylene terephthalate) yarns and fibers at higher speeds is desired. It is also desired that the practitioner be able to use the resultant yarns under the same conditions as yarns prepared at slower speeds.
Use of various additives to obtain benefits in spinning or other processing steps has been described in many patents. For instance, U.S. Pat. No. 4,475,330, which is incorporated herein by reference, discloses a high twist polyester multifilament yarn made from polyester filaments consisting essentially of (a) a copolymer of two or more monomers selected from the group consisting of ethylene terephthalate, trimethylene terephthalate and tetramethylene, and/or (b) a blend of two or more polymers of ethylene terephthalate, trimethylene terephthalate and tetramethylene terephthalate. The patent states that a woven or knitted crepe fabric obtained by employing such a high twist yarn has a desirable pebble configuration. The preferred polyester is comprised of 20% to 90% by weight of ethylene terephthalate units, and 80% to 10% by weight of trimethylene units and/or tetramethylene units. The examples show blends comprising 50 weight % poly(ethylene terephthalate), 25 weight % poly(tetramethylene terephthalate) and 25 weight % poly(trimethylene terephthalate). In addition, Example 6 describes polymer blends comprising 95 to 10% weight % poly(ethylene terephthalate) and 5 to 90 weight % poly(trimethylene terephthalate). This patent describes use of 3 to 15% of non-crystalline polymer, preferably styrene polymers or methacrylate polymers, to impart higher twist setting ability. Example 7 shows use of polystyrene with poly(ethylene terephthalate), poly(tetramethylene terephthalate), and blends thereof.
U.S. Pat. Nos. 4,454,196 and 4,410,473, which are incorporated herein by reference, describe a polyester multifilament yarn consisting essentially of filament groups (I) and (II). Filament group (I) is composed of polyester selected from the group poly(ethylene terephthalate), poly(trimethylene terephthalate) and poly(tetramethylene terephthalate), and/or a blend and/or copolymer comprising at least two members selected from these polyesters. Filament group (II) is composed of a substrate composed of (a) a polyester selected from the group poly(ethylene terephthalate), poly(trimethylene terephthalate) and poly(tetramethylene terephthalate), and/or a blend and/or copolymer comprising at least two members selected from these polyesters, and (b) 0.4 to 8 weight % of at least one polymer selected from the group consisting of styrene type polymers, methacrylate type polymers and acrylate type polymers. The filaments can be extruded from different spinnerets, but are preferably extruded from the same spinneret. It is preferred that the filaments be blended and then interlaced so as to intermingle them, and then subjected to drawing or draw-texturing. The Examples show preparation of filaments of type (II) from poly(ethylene terephthalate) and polymethylmethacrylate (Example 1) and polystyrene (Example 3), and poly(tetramethylene terephthalate) and polyethylacrylate (Example 4). Poly(trimethylene terephthalate) was not used in the examples.
JP 56-091013, which is incorporated herein by reference, describes an undrawn polyester yarn containing 0.5 to 10% by weight of a styrenic polymer having a degree of polymerization of 20 or higher. The fibers elongation is increased. The polyesters mentioned are poly(ethylene terephthalate), poly(tetramethylene terephthalate), polycyclohexane dimethylene terephthalate and polyethylene-2,6-naphthalene dicarboxylate.
JP 11-189925, which is incorporated herein by reference, describes the manufacture of sheath-core fibers comprising poly(trimethylene terephthalate) as the sheath component and a polymer blend comprising 0.1 to 10 weight %, based on the total weight of the fiber, polystyrene-based polymer. According to this application, processes to suppress molecular orientation using added low softening point polymers such as polystyrene did not work. (Reference is made to JP 56-091013 and other patent applications.) It states that the low melting point polymer present on the surface layer sometimes causes melt fusion when subjected to a treatment such as false-twisting (also known as “texturing”). Other problems mentioned included cloudiness, dye irregularities, blend irregularities and yarn breakage. According to this application, the core contains polystyrene and the sheath does not. Example 1 describes preparation of a fiber with a sheath of poly(trimethylene terephthalate) and a core of a blend of polystyrene and poly(trimethylene terephthalate), with a total of 4.5% of polystyrene by weight of the fiber.
It is desired to increase productivity in the manufacture of poly(trimethylene terephthalate) yarns, particularly partially oriented yarns, spun drawn yarns, and bulked continuous filament yarns, and in the manufacture of staple fibers, by using a high speed spinning process, without deterioration of the filament and yarn properties. It is further desired for these yarns to be useful in preparing products, such as textured yarns, fabrics and carpets, under the same or similar conditions to those used for poly(trimethylene terephthalate) yarns prepared at slower speeds.